[Lustre-discuss] Checksums of files on disk

[Christopher J.Walker]

The application I use, StoRM[1] can store checksums on disk in an
extended user attribute - and use that to ensure the integrity of files
on disk. The algorithm currently used is adler32. The intention is to
perform end to end checksumming from file creation through storage,
transfer over the WAN and storage at a site.

Looking at
http://wiki.lustre.org/manual/LustreManual20_HTML/ManagingFileSystemIO.html#50438211_pgfId-1291975

I see that Lustre has some checksum support (though not for checksumming
the file on the OST - so we'd still need to use the user attribute for
that).


http://wiki.lustre.org/manual/LustreManual18_HTML/LustreTuning.html#50651264_pgfId-1291287


Is the value of the checksum user accessible? Or to be more specific,
I'd potentially get a big speedup if I were able to ask the diskserver
to tell me the checksum of a file without actually transferring it over
the network. Is it easy to do this?

Chris

[1] http://storm.forge.cnaf.infn.it/home This is an SRM implementation
we use to give an grid authentication to our storage (we store data for
the LHC).